Fix error message display for InAppNotification used in Sample App

[michael-hawker]

We missed updating a template somewhere, so fatal errors aren't displaying in the Sample App. Ideally this message never appears, this is being surfaced from our issues with ICommand in the ListView samples. #4039

PR Type

What kind of change does this PR introduce?

• Sample app changes

What is the current behavior?

Error box appears blank.

What is the new behavior?

Error message shows exception message.

PR Checklist

Please check if your PR fulfills the following requirements:

• Tested code with current supported SDKs
• Pull Request has been submitted to the documentation repository instructions. Link:
• Sample in sample app has been added / updated (for bug fixes / features)
  • Icon has been created (if new sample) following the Thumbnail Style Guide and templates
• New major technical changes in the toolkit have or will be added to the Wiki e.g. build changes, source generators, testing infrastructure, sample creation changes, etc...
• Tests for the changes have been added (for bug fixes / features) (if applicable)
• Header has been added to all new source files (run build/UpdateHeaders.bat)
• Contains NO breaking changes

Other information

[ghost]

Thanks michael-hawker for opening a Pull Request! The reviewers will test the PR and highlight if there is any conflict or changes required. If the PR is approved we will proceed to merge the pull request 🙌

[ghost]

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[Rosuavio]

Good change. I think its worth mentioning here we still can get errors in samples after they load and that cause the sample app to crash. #4063.